According to introductions from a basic principle of a multi-antenna communication precoding and feedback technology, in a wireless communication system, a transmitting end and a receiving end acquire higher rates by using multiple antennae in a spatial multiplexing form. Compared with an ordinary spatial multiplexing method, an enhanced technology refers to that: the receiving end feeds channel information back to the transmitting end, and the transmitting end uses a transmission precoding technology according to the obtained channel information, so that the transmission performance can be greatly improved. In Single-User Multi-input Multi-output (MIMO) (SU-MIMO), channel feature vector information is directly used to perform precoding; and in Multi-User MIMO (MU-MIMO), relatively accurate channel information is needed. In a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), the channel information is fed back by mainly utilizing a simple single-codebook feedback method, and the performance of an MIMO transmission precoding technology more depends on the accuracy of feedback of a codebook therein.
A basic principle of codebook-based channel information quantized feedback is simply elaborated here as follows. If a limited feedback channel capacity is Bbps/Hz, the number of available code words is N=2B. A feature vector space of a channel matrix is quantized to form a codebook space ={F1, F2 . . . FS}. The transmitting end and the receiving end jointly save or generate this codebook  (the same for the transmitting end and the receiving end) in real time. For each channel implementation H, the receiving end selects a code word {circumflex over (F)} most matched with the channel implementation H from the codebook space  according to a certain criterion, and feeds a sequence number i (code word sequence number) of the code word {circumflex over (F)} back to the transmitting end. Here, the code word sequence number is referred to as a Precoding Matrix Indicator (PMI) in a codebook. The transmitting end finds the corresponding precoding code word {circumflex over (F)} according to the sequence number i, so as to obtain corresponding channel information, {circumflex over (F)} representing feature vector information of a channel. Herein, a channel H is generally obtained by channel measurement according to a channel measurement reference signal.
Generally speaking, the codebook space  may be further divided into codebooks corresponding to a plurality of Ranks, and each Rank will correspond to a plurality of code words to quantize a precoding matrix formed by channel feature vectors under this Rank. The Rank of a channel is equal to the number of non-zero feature vectors, so that generally speaking, there will be N columns of code words when the Rank is N. Therefore, the codebook space  may be divided into a plurality of sub-codebooks according to different Ranks. Table 1 is a diagram of a codebook divided into a plurality of sub-codebooks according to a Rank. As shown in Table 1:
TABLE 1 Layer number v (Rank)12. . .N  1  2. . .  NCode word vectorCode word vector set. . .Code word vector setset having columnhaving columnhaving columnnumber 1number 2number N
where when Rank>1, code words needing to be stored are all in a matrix form, a codebook in an LTE protocol adopts a codebook quantized feedback method, and actually, a precoding codebook and a channel information quantized codebook in the LTE have the same meaning. Hereinafter, for the sake of unification, a vector may be regarded as a one-dimension matrix.
Feedback contents of a 3GPP protocol about Channel State Information (CSI) introduce some contents relevant to channel information feedback in the LTE. Contents concerned in the disclosure are channel Rank Indication (RI) information and PMI information, and a Channel Quality Indication (CQI) may be fed back together with a PMI. CSI feedback includes: a CQI, a PMI and an RI.
The CQI is an index for measuring the downlink channel quality. In 36-213 protocols, the CQI is expressed by integer values 0-15, which respectively represent different CQI grades, different CQIs corresponding to respective Modulation and Coding Schemes (MCS). The RI is used to describe the quantity of spatial independent channels, and corresponds to a rank of a channel response matrix. Under open-loop spatial multiplexing and closed-loop spatial multiplexing modes, a User Equipment (UE) needs to feed RI information back, and under other modes, the UE does not need to feed RI information back. The rank of the channel matrix corresponds to a layer. The PMI feeds optimum precoding information back, and on the basis of index feedback, a code word most matching the feature of a current channel in an appointed codebook is indicated.
A concept of a CSI process is also introduced into the 3GPP, a base station may configure a plurality of CSI processes for a terminal, each CSI process is equivalent to a feedback process, and all CSI processes are independent of each other, and can perform parameter configuration respectively.
A CSI process includes configuration of a channel measurement part, and configuration of an interference measurement part and a feedback mode. The channel measurement part generally specifies a set of non-zero power CSI-RS for channel measurement, the interference measurement part generally specifies a set of IMR resource configurations for interference measurement, and IMR resources may generally be a set of zero power CSI-RS.
In the related art, a reference signal is a full-dimension reference signal generally by default, namely a physical antenna and a measurement reference signal port are one-to-one mapping, a channel measurement method is relatively simple, and a CSI quantized feedback technology based on an RI/PMI/CQI implicit feedback method is also relatively single.
With the development of an MIMO technology, a great number of new technologies, e.g., a measurement technology based on a precoding CSI-RS reference signal and a new feedback technology such as a horizontal/vertical fractional dimension feedback technology, emerge. Although some new technologies have good performances under some scenarios, performance losses will be brought under some scenarios. Therefore, it becomes very important to be able to quite flexibly perform various measurements and feedbacks, so good performance can be guaranteed, and meanwhile, good measurement and feedback robustness can be guaranteed.
At present, any effective solution has not been proposed yet for the problem that in the related art the reference signal measurement and feedback technologies are not flexible.